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[unix-history] / usr / src / sbin / dmesg / dmesg.c

static char *sccsid = "@(#)dmesg.c      4.2 (Berkeley) 83/01/02";
/*
*      Suck up system messages
*      dmesg
*              print current buffer
*      dmesg -
*              print and update incremental history
*/

#include <stdio.h>
#include <sys/param.h>
#include <nlist.h>
#include <signal.h>
#include <sys/vm.h>
#include <sys/msgbuf.h>

struct  msgbuf msgbuf;
char    *msgbufp;
int     sflg;
int     of      = -1;

struct  msgbuf omesg;
struct  nlist nl[2] = {
       { "_msgbuf" },
       { "" }
};

main(argc, argv)
char **argv;
{
       int mem;
       register char *mp, *omp, *mstart;
       int timeout();
       int samef;

       signal(SIGALRM, timeout);
       alarm(30);
       if (argc>1 && argv[1][0] == '-') {
               sflg++;
               argc--;
               argv++;
       }
       if (sflg) {
               of = open("/usr/adm/msgbuf", 2);
               read(of, (char *)&omesg, sizeof(omesg));
               lseek(of, 0L, 0);
       }
       sflg = 0;
       nlist(argc>2? argv[2]:"/vmunix", nl);
       if (nl[0].n_type==0)
               done("No namelist\n");
       if ((mem = open((argc>1? argv[1]: "/dev/kmem"), 0)) < 0)
               done("No mem\n");
       lseek(mem, (long)nl[0].n_value, 0);
       read(mem, &msgbuf, sizeof (msgbuf));
       if (msgbuf.msg_magic != MSG_MAGIC)
               done("Magic number wrong (namelist mismatch?)\n");
       mstart = &msgbuf.msg_bufc[omesg.msg_bufx];
       omp = &omesg.msg_bufc[msgbuf.msg_bufx];
       mp = msgbufp = &msgbuf.msg_bufc[msgbuf.msg_bufx];
       samef = 1;
       do {
               if (*mp++ != *omp++) {
                       mstart = msgbufp;
                       samef = 0;
                       pdate();
                       printf("...\n");
                       break;
               }
               if (mp == &msgbuf.msg_bufc[MSG_BSIZE])
                       mp = msgbuf.msg_bufc;
               if (omp == &omesg.msg_bufc[MSG_BSIZE])
                       omp = omesg.msg_bufc;
       } while (mp != mstart);
       if (samef && omesg.msg_bufx == msgbuf.msg_bufx)
               exit(0);
       mp = mstart;
       do {
               pdate();
               if (*mp && (*mp & 0200) == 0)
                       putchar(*mp);
               mp++;
               if (mp == &msgbuf.msg_bufc[MSG_BSIZE])
                       mp = msgbuf.msg_bufc;
       } while (mp != msgbufp);
       done((char *)NULL);
}

done(s)
char *s;
{
       register char *p, *q;

       if (s && s!=(char *)omesg.msg_magic && sflg==0) {
               pdate();
               printf(s);
       }
       write(of, (char *)&msgbuf, sizeof(msgbuf));
       exit(s!=NULL);
}

pdate()
{
       extern char *ctime();
       static firstime;
       time_t tbuf;

       if (firstime==0) {
               firstime++;
               time(&tbuf);
               printf("\n%.12s\n", ctime(&tbuf)+4);
       }
}

timeout()
{
       done("Buffer file screwed up\n");
}